Rectifier and method of making the same



Oct. 25, 1949. I 1.. B. HAIGH 2,485, 3

RECTIFIER AND METHOD OF MAKING THE SAIE Origin]. Fil'ed Aug, 14, 1943 INVEN TOR 155A IE 5. 114 6 Patented Oct. 25, 1949 Q RECTIFIER AND METHODOF MAKING THE SAME Leslie B. Haigh, West Orange, N. J., as'signor toFederal Telephone and Radio Corporation, Newark, N. J a corporation ofDelaware Original application August 14, 1943, Serial No. 498,654.Divided and this application January 3, 1947, Serial No. 720,035 1 6Claims. (CL 175-366) This invention relates to improvements inrectifiers and methods of making the same. and more particularly torectifiers of the dry contact type, such as selenium rectifiers.

This application is a division of application, Serial No. 498,654, filedAugust 14, 1943, now Patent No. 2,419,602, issued April 29, 1947.

An object of this invention is directed to the provision of improved,small, low-capacity rectifiers.

Another object of this invention is to provide a small rectifier ofsimple design and high efiiciency.

A further object of this invention is directed toward an improved andsimplified method of making rectifiers.

Generally speaking, this invention may be defined as comprising theconstructions and combinations recited in the annexed claims andillustrated in the drawings accompanying and forming a part of thisapplication, wherein:

Fig. 1 is a longitudinal cross-sectional view of a preferred form ofrectifier construction in accordance with the present invention;

Fig. 2 is a top plan view of the rectifier illustrated in Fig. 1; and

Fig. 3 is a horizontal cross-sectional view taken along the line 3-3 ofFig. 1.

In the form of invention shown in Figs. 1, 2

v and 3, it will be seen that the rectifier is built-up on a metal baseplate 40 having a raised portion i2, preferably substantially centrallylocated with respect to the plate as a whole, upon which is formed inany suitable manner known to the art, a thin selenium layer M. A layerof insulation l6, which may be a thermoplastic artificial insulationsuch as polystyrene or may be formed of insulating paper is placed onthe base It! and is provided with a through opening uncovering theselenium spot it. A lead wire 18 is placed on the insulating layer 16,passing over the opening therethrough and a second layer of insulation20 is applied over the lead wire l8 and joining with the firstinsulating layer It. The second insulating layer is also provided with athrough opening substantially aligned with the opening in the insulatinglayer i6. Counter-electrode alloy 22 is then melted and poured throughthe aligned openings forming contact with the selenium layer It and, atthe same time fusing with a portion of the lead wire 18 and thus holdingthe latter in position. In accordance with the construction of thedescribed modification, the base plate is preferably formed with fourears 24 at its corners and these are bent upwardly and over 2 the topinsulating layer 20 pressing the parts against the base plate III toform a unitary structure. A second lead wire 26 may be soldered-orotherwise attached to the base plate I0.

It will be seen from the description just given that the describedconstruction provides a very simple and yet extremely emcient lowcapacity rectifier. The selenium spot and the counterelectrode area incontact therewith are kept small, thus providing for high currentdensity and improved efiiciency of the rectifier. In the drawings, thethickness of the parts such as the metal plate It, selenium layer I4 andthe insulatinglayers 16 and 20 have been exaggerated for the purposes ofclear illustration, and while the invention is not intended to belimited to any particular size, it may be mentioned that rectifiers ofthe type described have been manufactured with a length of about of aninch, a

width of about A of an inch and a thickness of less than of an inch.Additionally, while the integral legs formed on the base plate are shownto extend longitudinally thereof, it will be obvious to those skilled inthis art that these built-up and turned-over legs could projectlaterally from the base plate as well. After assembly of the exposedportions of the rectifier, including the base plate, the turned-overlegs, the counter-electrode alloy and parts of the lead wires can befurther insulated as by painting, if desired.

Various changes and modifications coming within the scope of the presentinvention will occur to those skilled in this art. The base plate Itwill preferably consist of a metal containing iron but other metalssuitable for use with selenium for the purposes of rectification may beused, or the base plate l0 may be formed of any metal coated with aniron-containing alloy. The manner in which the selenium is applied tothe base plate is of no particular importance with respect to thepresent invention and variousmethods' known to the art may be utilized,while after assembly, the rectifier may be electroformed in the usualmanner to create the desired barrier said wire passing over saidopening, a second layer of insulation above said lead wire and having anopening therethrough substantially coaxial with the opening in the firstinsulating layer, a counter-electrode alloy extending through said twoopenings, about said lead wire and to said selenium layer, and integralextensions on said base plate bent upwardly and over the secondinsulating layer to hold all the parts together as an integral unit.

2. A rectifier comprising, in combination, a metallic base plate, alayer of selenium on said base plate, an insulating layer supported bysaid base plate and having a small opening therethrough exposing a smallarea of selenium, alead wire on said insulating layer passing acrosssaid opening, counter-electrode alloy in said opening, fused to saidlead wire and contacting the selenium layer, a second insulating layerover said lead wire and the first insulating layer, and integralextensoins on said base plate bent upwardly and over the secondinsulating layer to hold all the parts together as an integral unit.

3. The combination according to claim 2, in which said second insulatinglayer has an opemng therethrough substantially aligned with the openingin the first insulating layer, and in which I said alloy extends throughboth openings to the selenium layer.

4. The combination according to claim 2, in which said selenium layercomprises a small spot of selenium on the base plate, corresponding insize to the size of the opening in the first insulating layer.

5. A rectifier comprising, in combination, a metallic base plate havinga raised substantially central portion, a layer of selenium on saidraised portion, a first insulating layer on said base plate,

having an'opening exposing said selenium layer, a lead wire on saidinsulating layer having a portion extending over said opening, a secondlayer of insulation on said first insulation, covering said lead wireand having an opening aligned with the opening in the first insulatinglayer, counterelectrode alloy in said openings, fused to the lead wireand contacting the selenium layer, and integral extensions on said baseplate bent upwardly and over said second insulating layer to hold saidparts together.

6. A rectifier comprising, in combination a metallic base plate, a layerof insulating material covering the major portion of the top surfacearea of said base plate, said layer having an opening extendingthereth'rough, a spot of selenium covering only that portion of saidbase plate top surface that is bounded by said opening, a lead wiresupported on said insulation and passing over said opening, a secondlayer of insulation above said lead wire and having an opening abovesaid firstnamed opening, and a counter-electrode element extendingthrough said openings into contact with said lead wire and seleniumspot.

LESLIE B. HAIGH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Nov. 28,1935

